You need to look for Technical Manuals - TMs - as well.

The loading of equipment is *in general* covered in one or two FMs, but the loading of specific equipment including tie-downs, chocks, and so forth would be covered in the equipment TM. Starting about 1950-ish this info is very good. In the TMs of the previous decade it was spotty.

The US Army Heritage and Education Center has quite a few manuals digitized:

http://www.ahco.army.mil/site/index.jsp > Military Publications

There are a number at the Combined Arms Research Library as well:

http://cgsc.cdmhost.com/cdm4/search.php >Obsolete Military Manuals

This public upload site has a number as well:

www.scribd.com

And, of course, Ebay.

KL